This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:
ASIC application specific integrated circuit
CPU central processing unit
DMA direct memory access
DRAM dynamic random access memory
eMMC embedded multimedia card
exFAT extended file allocation table
HW hardware
IO input output
JEDEC joint electron device engineering council
LBA logical block address
MMM, MM mass memory module or memory module
MMC multi media card
MMCO memory module controller
MRAM magnetic random access memory
OS operations system
P2L physical to logical
PCRAM phase change random access memory
RAM random access memory
RRAM resistive random access memory
SATAIO serial advanced technology attachment international organization
SCSI small computer system interface
SD secure digital
SM system memory or host system memory
SRAM static random access memory
SSD solid state drive
SW software
UFS universal flash storage
Various types of flash-based mass storage memories currently exist. A basic premise of mass storage memory is to hide the flash technology complexity from the host system. A technology such as eMMC is one example. A managedNAND type of memory can be, for example, an eMMC, SSD, UFS or a microSD.
FIG. 1A reproduces FIG. 2 from JEDEC Standard, Embedded MultiMediaCard (eMMC) Product Standard, High Capacity, JESD84-A42, June 2007, JEDEC Solid State Technology Association, and shows a functional block diagram of an eMMC. The JEDEC eMMC includes, in addition to the flash memory itself, an intelligent on-board controller that manages the MMC communication protocol. The controller also handles block-management functions such as logical block allocation and wear leveling. The interface includes a clock (CLK) input. Also included is a command (CMD), which is a bidirectional command channel used for device initialization and command transfers. Commands are sent from a bus master to the device, and responses are sent from the device to the host. Also included is a bidirectional data bus (DAT[7:0]). The DAT signals operate in push-pull mode. By default, after power-up or RESET, only DAT0 is used for data transfer. The memory controller can configure a wider data bus for data transfer using either DAT[3:0] (4-bit mode) or DAT[7:0] (8-bit mode).
One non-limiting example of a flash memory controller construction is described in “A NAND Flash Memory Controller for SD/MMC Flash Memory Card”, Chuan-Sheng Lin and Lan-Rong Dung, IEEE Transactions of Magnetics, Vol. 43, No. 2, February 2007, pp. 933-935 (hereafter referred to as Lin et al.) FIG. 1B reproduces FIG. 1 of Lin et al., and shows an overall block diagram of the NAND flash controller architecture for a SD/MMC card. The particular controller illustrated happens to use a w-bit parallel Bose-Chaudhuri-Hocquengham (BCH) error-correction code (ECC) designed to correct random bit errors of the flash memory, in conjunction with a code-banking mechanism.